STEMS 



245 



elongating portion of a stem does not often extend more 

 than ten to twenty inches. Seedlings such as those of the 

 bean should be cultivated, and the region of growth, the 

 region of greatest growth, and the rate of growth determined. 

 To do this, each internode is marked with equally spaced 

 lines in India ink, and measuring these spaces at intervals. 



FIG. 212. Axillary (and therefore branch) thorns: A, honey locust; B, hawthorn. 



of one or two days will determine the facts referred to above 

 (Fig. 211). 



136. Subterranean stems. Since stems (or branches) 

 usually bear foliage leaves, any stem which does not is 

 spoken of as " modified." For example, branches that 

 become thorns (Fig. 212), tendrils (Fig. 213), leaf-like 

 structures (Fig. 193), etc., are thought of as stems diverted 

 from their ordinary use. 

 17 



